1. Field of the Invention
This invention relates generally to an electro-acoustic transducer, and more particularly to a loudspeaker having an improved vibrative member.
2. Description of the Prior Art
In recent year, various types of transducers utilizing a drive system have been developed for the purpose of reproducing high fidelity sounds.
As an example of the prior art transducers, there is proposed a so-called a ribbon type transducer. This type transducer is constructed with a magnetic circuit having at least one air gap, and a diaphragm having a conductor thereon and disposed in the air gap. In this case, when an electrical signal is applied to the conductor formed on the diaphragm, a sound is generated by the vibration of the diaphragm since the signal current flows through the conductor in the direction perpendicular to the magnetic field on the air gap.
In general, the diaphragm of an ordinary transducer has inherent vibration. When a signal having frequencies coincident with the inherent frequency of the diaphragm is applied thereto, the transducer or speaker emits an abnormal sound. In the art, in order to avoid the generation of such abnormal sounds, a damping material such as a glass-wool is brought into contact with the inner surface of the diaphragm to suppress its inherent vibrations. However, the above prior art damping material has a problem because it is impossible to bring the diaphragm into contact with the damping material uniformly and hence the desired effects can not be obtained. Further, when the speaker is assembled, it requires a number of steps to arrange the damping material and also the characteristics of speakers vary after the speakers are assembled.
It is also known to have a metallic mesh mounted on the inner surface of the vibrative member with a spacer and then glass-wool is placed between the metallic mesh and the diaphragm. This method, however, can not solve the above problem.